This invention relates to a multicolor printing apparatus and, more particularly, to a new improved printing apparatus which permits cut piece textile goods and unfished garments to be automatically screen printed in diverse colors with speed and accuracy thereby precluding time consuming hand registration or manual handling between printing stations.
Various methods have been used in the prior art for multicolor printing of cut textile pieces and finished garments, including manual and automatic operation. In either of these methods the basic problem of registration of the piece to be printed remains the same. In the manual operation, registration is achieved by hand at each individual station, and is chiefly dependent upon the operator's skill and speed in registering the object. In the automatic method, registration presents a different, though related problem. Not only must the work piece be accurately registered initially on the platen, but also each platen must itself be accurately registered to each successive printing machine in the printing cycle. To accomplish the initial registration of the work piece on each platen during and between each successive printing station, a light adhesive coating is generally applied to the platen, onto which the work pieces may then be accurately registered by hand. The light adhesive coating grips the work piece and retains it in place on the platen. However, the difficulty of registering the platen to each individual printing station still remains, due to the imprecision inherent in all commonly used drive means. Registration of the platens to each printing station is, at best, correspondingly imprecise.
Therefore, a need arises for a precise and inexpensive method of registering and locking the platen to each successive printing station of a multicolor printing assembly. The subject invention accomplishes the necessary precise registration with a rotatable multiplaten assembly utilizing a unique indexing and locking means. With the subject invention it is possible to print five to seven different colors in substantial registration with one another, quickly and accurately. The subject indexer rotates the platens in unison to each successive printing station where a locking means engages and registers each platen at each station. Each printing press then prints that portion of the desired message or design on the selected color upon the registered object.
The ability of the subject invention to register and index a plurality of individual platens at successive stations in a printing operation permits selection of those printing presses which are most suitable for a particular application.
The indexer of the subject invention rotates a table about a central shaft or axis on which are mounted a plurality of equally spaced platens. The indexer includes a drive means which rotates an output shaft, at one end of which is connected a drive arm, which has rollers extending at right angles to the drive arm at opposite ends of the arm. Attached to the central shaft for revolution about the axis is a drive disc or wheel, having equally spaced, radially extending slots for accepting the rollers of the drive arm. As the drive arm rotates, a roller enters a slot and, continuing the drive arm's rotation about the output shaft, the roller urges the drive wheel in a circular motion until it emerges from the slot. The table and the plurality of platens are rotated by the drive wheel to the next station for the next step in the printing operation.
The registration of each platen at each station is accomplished by the locking mechanism. Pins extend from the circumference of the table at selected intervals. The locking mechanism comprises a latch having a recess for engaging these pins to register the platens to each station. The close conformance of the pin to the latch recess assures accurate registration. The latch engages and disengages the pin in a vertical fashion and is attached to its lower end to a lever arm which is pivoted at the opposite end. Between the ends of the lever arm is provided a cam follower which operates with a captivated cam revolving about the axis of rotation of, and in cooperation with the output shaft. In following the captivated cam the latching means is caused to reciprocate in a vertical fashion in conjunction with the start and finish of a half-rotation of the output shaft. Thus, as the roller of the drive arm enters a slot of the drive disc or wheel, the latching means quickly drops, releasing the table for rotation in conjunction with the urging of the drive arm. Upon the exit of the roller from the slot of the drive wheel, the latching means engages the registration pin on the succeeding platen, again registering all platens at each station. This sequence is repeated continuously. As each roller emerges from the slot, the opposite roller is in position to enter the next slot, after the printing is accomplished at that station.
The new and improved multicolor screen printing assembly provides considerable advantages in the manufacture and operation of the machine because of the reduced number of parts and simplicity of design. This, of course, contributes to the reduced cost of manufacture and maintenance and enlarges the number of applications of the machine.
It is therefore an object of the present invention to provide a new and improved multicolor printer which will allow the quick and accurate successive printing of a plurality of colors on a single object.
It is a further object of this invention to provide a new and improved multicolor printer of simplified design which is adaptable to a wide variety of uses.
It is a still further object of this invention to provide a multicolor printer in which the platen will be accurately registered during each printing cycle.